At the present time, many portable electronic devices, and in particular cellular telephones, incorporate a feature which allows the user to disable the keypad of the device. U.S. Pat. No. 5,241,583 describes a method which may be used to disable the keypad of a cellular telephone. In U.S. Pat. No. 5,241,583, the keypad of a cellular telephone is disabled by pressing a sequence of keys or pressing two keys at the same time. Another known way of disabling a keypad is by holding down a particular key in the keypad for a certain duration of time. Once the keypad has been disabled, it is usually re-enabled by pressing the same sequence of keys or the same key that was pressed to lock the device.
Disabling the keypad is useful to the user of the device, as it allows the inadvertent pressing of buttons to be avoided, for instance when the device is in the user's pocket.
However, currently a cellular telephone may only be disabled from the idle/data entry mode. If the user is editing text or watching a video clip on his telephone, he is also unable to disable the keypad at that point. This may be problematic if the user, for instance, writes part of an SMS message, but is distracted and has to put the telephone back into his pocket. At this point, keys may inadvertently be pressed. The user may also wish to let his child watch a video clip on the telephone. The child, however, may try to press some of the buttons on the keypad while the telephone is in the child's possession, which could lead to some of the settings on the telephone being altered and/or important data being lost.
It would be desirable to provide a mechanism for locking the keypad of a portable electronic device when the device is not in its idle/data entry mode.